In order to avoid longitudinal rips, tears or slits in conveyor belts with longitudinal tensile reinforcement such as ropes, wires, cords, or the like, hereinafter termed "longitudinal reinforcement strands," different arrangements, termed "transverse barriers", have been developed.
The known transverse barriers have transverse metal pieces such as bars, ropes, strands embedded in the conveying cover layer of the conveyor belt. Because of their cutting resistance these metal pieces are intended to free and eject the foreign object which has penetrated the conveyor belt.
These mechanical transverse barriers, although more robust than those known as "electrical barriers", offer only limited resistance to a penetrating foreign object and sometimes have considerable disadvantages.
A known transverse barrier for instance consists of wire strands embedded in the conveying cover layer of the conveyor belt. In case the top surface of the belt is damaged by the impacting, conveyed material, or in case the belt edges is damaged by engagement with an edge of the conveyor framework, the ends of the wire strands can emerge and cause injuries to people working at the conveying equipment or the conveying system itself can be imparied.
Because the mechanical transverse barriers may be partly torn out by the objects which penetrate into the conveyor belt, considerable damage is done to the conveyor belt, which can require very difficult repairs.
In a known conveyor belt (German printed application DT-OS No. 1,935,266) thread-like strengtheners, embedded in the cover layer of the belt, are used as mechanical transverse barriers. The threads run at an angle to the longitudinal direction of the belt, from the edges of the belt towards the center in opposite directions.
A conveyor belt furnished with such mechanical barrier is intended to have less transverse rigidity and an undisturbed straight run. Furthermore such a conveyor belt is to have a high insensibility towards cut- and separation destruction. However, it is quite expensive to produce such a conveyor belt. If metal reinforcement strands (inlays) are used additional space is necessary; the top cover layer has to be adequately thick in order to accommodate the metal reinforcement.
In another known conveyor belt (German printed DT-AS No. 2,301,290) the mechanical transverse barriers are loops made from flexible materials enclosing at least two tensile elements. This conveyor belt is said to be protected against ripping without interfering with its flexibility or bending ability in the transverse direction. The loops are grouped and distributed across the width of the belt. Whereby each group forms a transverse barrier. The distance between the single groups can be chosen freely. This belt has the disadvantage of high production cost, if loops are closely spaced, or, if spacing is increased to lower cost, exposing larger areas of the belt to ripping.